I've noticed that if the slash attack is set to the down+special or up+special keys, the default direction of attack is to the right, regardless of the direction the character is facing. I found this bug affected the Mantibyte Arm, Subprogram Arm 2, Scythe Claw, and Preato Arm, (but, in case I'm missing any, I assume it affects all slash attack parts). Additionally, if two slash parts are equipped and mapped to special and up/down+special, the up/down+special will redirect the other special to the right, (i.e. if you up/down+special first, the directionless special will strike to the right, even if the character is facing to the left), and this persists until you press left or right.

Note: This also appears to affect the Subprogram Arm 1, (despite shovel being a different attack).